Iridium-catalyzed carbonylation process for the production of a carboxylic acid
A process for the production of a carboxylic acid having n+1 carbon atoms comprises (a) carbonylating with carbon monoxide in a first reaction zone at elevated temperature and pressure an alkyl alcohol having n carbon atoms and/or a reactive derivative thereof to produce a carboxylic acid having n+1 carbon atoms in a liquid reaction composition comprising carboxylic acid product, an iridium catalyst, an alkyl halide co-catalyst, water, an ester of the carboxylic acid product and the alkyl alcohol, and optionally one or more promoters, (b) withdrawing from the first reaction zone at least a portion of the liquid reaction composition together with dissolved and/or entrained carbon monoxide, and passing at least a portion of the withdrawn liquid reaction composition and carbon monoxide to a second reaction zone, ((c)reacting at least 1% of the dissolved and/or entrained carbon monoxide in the withdrawn reaction composition by further carbonylation at elevated temperature and pressure in the second reaction zone to produce further carboxylic acid product.
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Claims
1. A process for the production of a carboxylic acid having n+1 carbon atoms which process comprises (a) carbonylating with carbon monoxide in a first reaction zone at elevated temperature and pressure an alkyl alcohol having n carbon atoms and/or a reactive derivative thereof to produce a carboxylic acid having n+1 carbon atoms in a liquid reaction composition comprising carboxylic acid product, an iridium catalyst, an alkyl halide co-catalyst, water, an ester of the carboxylic acid product and the alkyl alcohol, and optionally one or more promoters, (b) withdrawing from the first reaction zone at least a portion of the liquid reaction composition together with dissolved and/or entrained carbon monoxide, and passing at least a portion of the withdrawn liquid reaction composition and carbon monoxide to a second reaction zone, (c) reacting at least 1% of the dissolved and/or entrained carbon monoxide in the withdrawn reaction composition by further carbonylation at elevated temperature and pressure in the second reaction zone while keeping the added ionic iodide salt concentration in the reaction composition at less than 500 ppm I.sup.- to produce further carboxylic acid product.
2. A process according to claim 1 wherein substantially all the liquid reaction composition together with dissolved and/or entrained carbon monoxide withdrawn from the first reaction zone is passed to the second reaction zone.
3. A process according to claim 1 wherein methanol and/or methyl acetate are carbonylated with carbon monoxide in the first reaction zone.
4. A process according to claim 1 wherein the concentrations of the ester of the carboxylic acid product and the alkyl alcohol in the first and second reaction zones are independently in the range from 3 to 35% by weight.
5. A process according to claim 1 wherein the concentrations of water in the liquid reaction compositions in the first and second reaction zones are independently in the range from 1 to 10% by weight.
6. A process according to claim 1 wherein the concentrations of alkyl halide in the liquid reaction compositions in the first and second reaction zones are independently in the range from 2 to 16% by weight.
7. A process according to claim 1 wherein the concentrations of the iridium catalyst in the liquid reaction compositions of the first and second reactors is in the range from 100 to 6000 ppm by weight of iridium.
8. A process according to claim 1 wherein the liquid reaction compositions additionally comprise as promoter one or more of ruthenium and osmium.
9. A process according to claim 8 wherein the promoter is present in the liquid reaction compositions at a molar ratio of each promoter to iridium of up to 10:1.
10. A process according to claim 1 when operated in the absence of added iodide salt.
11. A process according to claim 1 wherein in the first reaction zone the temperature of the carbonylation reaction is in the range 150 to 220.degree. C. and the pressure is in the range 15 to 50 barg.
12. A process according to claim 1 wherein in the second reaction zone the reaction temperature is in the range 150 to 230.degree. C. and the pressure is in the range 15 to 100 barg.
13. A process according to claim 1 wherein the residence time of liquid reaction composition in the second reaction zone is in the range 5 to 300 seconds.
14. A process for the production of a carboxylic acid having n+1 carbon atoms which process comprises (a) carbonylating with carbon monoxide in a first reaction zone at elevated temperature and pressure an alkyl alcohol having n carbon atoms and/or a reactive derivative thereof to produce a carboxylic acid having n+1 carbon atoms in a liquid reaction composition comprising carboxylic acid product, an iridium catalyst, an alkyl halide co-catalyst, water, an ester of the carboxylic acid product and the alkyl alcohol, and optionally one or more promoters, (b) withdrawing from the first reaction zone at least a portion of the liquid reaction composition together with dissolved and/or entrained carbon monoxide, and passing at least a portion of the withdrawn liquid reaction composition and carbon monoxide to a second reaction zone, (c) reacting at least 1% of the dissolved and/or entrained carbon monoxide in the withdrawn reaction composition by further carbonylation at elevated temperature and pressure in the second reaction zone to produce further carboxylic acid product, wherein there is introduced to the second reaction zone carbon monoxide in addition to that introduced to the zone as dissolved and/or entrained carbon monoxide.
15. A process according to claim 14 wherein the additional carbon monoxide is high pressure offgas from the first reaction zone.
16. A process according to claim 1 wherein greater than 25% of the dissolved and/or entrained carbon monoxide in the withdrawn reaction composition from the first reaction zone is consumed in the second reaction zone.
17. A process according to claim 1 wherein at least 95% of the dissolved and/or entrained carbon monoxide in the withdrawn reaction composition from the first reaction zone is consumed in the second reaction zone.
18. A process for the production of a carboxylic acid having n+1 carbon atoms which process comprises (a) carbonylating with carbon monoxide in a first reaction zone at elevated temperature and pressure an alkyl alcohol having n carbon atoms and/or a reactive derivative thereof to produce a carboxylic acid having n+1 carbon atoms in a liquid reaction composition comprising carboxylic acid product, an iridium catalyst, an alkyl halide co-catalyst, water, an ester of the carboxylic acid product and the alkyl alcohol, and optionally one or more promoters, (b) withdrawing from the first reaction zone at least a portion of the liquid reaction composition together with dissolved and/or entrained carbon monoxide, and passing at least a portion of the withdrawn liquid reaction composition and carbon monoxide to a second reaction zone, (c) reacting at least 1% of the dissolved and/or entrained carbon monoxide in the withdrawn reaction composition by further carbonylation at elevated temperature and pressure in the second reaction zone to produce further carboxylic acid product, wherein a second liquid composition is withdrawn from the second reaction zone and the amount of carbon monoxide in said second liquid composition is reduced to maintain at least 20% by volume of the dissolved and/or entrained gases therein and is comprised of unreacted and/or dissolved and/or additional carbon monoxide.
19. A process according to claim 1 wherein the first and second reaction zones are maintained in separate reaction vessels with means for withdrawing from the first reaction vessel and passing to the second reaction vessel liquid reaction composition from the first reaction vessel with dissolved and/or entrained carbon monoxide.
20. A process according to claim 19 wherein the second reaction vessel comprises a section of pipe between the first reaction vessel and a liquid reaction composition flashing valve.
21. A process according to claim 19 wherein the first reaction vessel is operated as a liquid-full back mixed reactor in fluidic communication with the second reaction vessel.
22. A process according to claim 21 wherein the second reactor is operated as a bubble column reactor with limited back mixing.
23. A process according to claim 1 wherein the second reaction zone comprises a relatively quiescent reaction zone within a reactor in the main body of which is housed the first reaction zone.
24. A process according to claim 23 wherein the reactor is partitioned into a first reaction zone forming a major proportion of the reaction space and having agitation means therein and a second smaller reaction zone having no agitation means, the second reaction zone being in liquid communication with the first reaction zone.
25. A process according to claim 1 wherein the carbon monoxide partial pressure in the first and second reaction zones is independently in the range 1 to 15 bar.
26. A process according to claim 1 wherein the carboxylic acid product is acetic acid.
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Type: Grant
Filed: Dec 4, 1997
Date of Patent: Aug 3, 1999
Assignee: BP Chemicals Limited
Inventors: George Ernest Morris (Cottingham), John Glenn Sunley (Cottingham)
Primary Examiner: Samuel Barts
Assistant Examiner: Rosalynd Keys
Law Firm: Morgan & Finnegan, L.L.P.
Application Number: 8/984,996
International Classification: C07C 5112; C07C 5114;
